This section provides background information related to the present disclosure which is not necessarily prior art.
It is often desired to power a device with rotary power that is transmitted from a prime mover either directly or through an endless power transmitting element, which could employ a belt, a chain and/or a toothed gear. Such devices could, for example be connected to the engine of a motor vehicle via an accessory drive or a timing drive and could include a pump (e.g., water pump, vacuum pump, power steering pump, hydraulic pump, air compressor, air conditioning compressor), a means for generating electricity (e.g., alternator, generator, starter-alternator, starter-generator), a supercharger, and/or a fan, for example.
It will be appreciated that in situations when the output of the device is not needed or desired, operation of the device will be associated with reduced efficiency of the prime mover. In an automotive context for example, it is not necessary to constantly operate an air conditioning compressor and as such, the operation of the air conditioning compressor when it is not needed reduces the overall fuel efficiency of the engine. To overcome this drawback, it was known in the art to provide a clutch to selectively operate the device. Such clutches typically required some sort of power, usually electrical power, to permit rotary power to be transmitted through the clutch to drive the device. While such clutches are suitable for their intended purposes, such clutches are nonetheless susceptible to improvement.